In contemporary vehicle structures (passenger cars, buses, trains, etc.), acoustic damping compounds with damping/soundproofing functions are provided in various components of the vehicle structures, such as accessories, panels, roofing, and flooring, to reduce or prevent transmission of vibrations generated by the structures and noise created by these vibrations. Common acoustic damping compounds include injectable and extrudable compounds based on bitumen, rubber, epoxy, and water-based (acrylate) dispersions whose matrix conforms to the shape of the vehicle. These acoustic damping compounds are usually applied to the surface of the vehicle frame and various application sites in the vehicle.
In order to prevent vibrations of the outer panels, prevent knocking of various components in the vehicle, and ensure the proper distance between components in a vehicle structure, a so-called undercoating is preferably applied between the outer panels and the roof arch, and between protective components and reinforcing components. This undercoating can reinforce the vehicle structure and the undercoating material can simultaneously function as an adhesive or sealant.
A composition integrating damping/soundproofing functions with the functions of an undercoating is the thermally curable composition disclosed in Patent Document 1, which comprises (a) an olefinic double-bond-containing polymer or copolymer based on a diene- and/or aromatic-substituted olefin and (b) a vulcanization system. When a composition described in Patent Document 1 is used, it serves as an integrated acoustic damping compound and undercoating, which previously required applying a plurality of different materials. This simplifies the manufacturing process and manufacturing equipment, and thus reduces costs. Because this composition is “pumpable” that is, can be distributed (pumped) by a pump, it can be applied by a robot and used advantageously in a vehicle production process which is highly automated.
However, compositions used in vehicle structures such those of automobiles will presumably be used in low-temperature environments and must have good low-temperature characteristics. A composition (one-part bonding agent, sealant, or coating) suitable for use in vehicle production having high tensile shear strength and high impact peel strength at low temperatures was disclosed in Patent Document 2 in the form of a high-temperature thermally curable reaction composition based on a natural and/or synthetic olefinic double-bond containing elastomer and a vulcanizer and containing a liquid polyene and polybutadiene.